1. Field of the Invention
This invention relates to an internal combustion engine equipped with a regenerator.
2. Description of the Related Art
Generally, when an internal combustion engine is running at temperatures under a predetermined temperature around combustion chambers, fuel atomization supplied to the combustion chambers deteriorates and so did exhaust gas emission due to quenching around walls of the combustion chambers.
In order to obviate this problem, an internal combustion engine equipped with a regenerator is being developed which can accumulate heat generated from combustion when the engine is running. Then the accumulated heat is supplied to the engine when the engine is not running or the engine needs to be started. However, the amount of heat accumulated in the regenerator is limited, then a technology which utilizes the limited amount of heat effectively is being disclosed.
According to Japanese patent application Laid-open No. 6-185359, the engine is equipped with a first coolant channel which supplies water coolant to a cylinder block, a second coolant channel which supplies coolant to a cylinder head independently and is connected to a regenerator.
A regenerator in the internal combustion engine which is formed according to the above prior technology supplies heat to the cylinder head intensively through the second coolant channel. The heat is emitted from the regenerator when the engine is under cold conditions. As mentioned above, the limited amount of heat can be supplied to the internal combustion engine effectively by supplying the heat accumulated in the regenerator to a cylinder head intensively. Therefore, emission performance and fuel efficiency can be improved.
However, a coolant channel, which is connected to the cylinder head and the cylinder block, flows into both the cylinder head and the cylinder block. Water coolant flows into devices such as a radiator and a heater core which are located outside the internal combustion engine since some of the water coolant channels are connected to these devices. If heat is supplied to a part where heat supply is not needed, the temperature of coolant drops unnecessarily which increases heat consumption in the regenerator. If a regenerator with large volume is to be installed in a vehicle, a quite large device is needed which makes the installation difficult. Even if the installation is possible, fuel consumption and automobile performance deteriorates due to the increased mass.
In this connection, an internal combustion engine needs to be warmed up before being started to start the internal combustion engine under warm conditions. However, it is difficult to precisely grasp the timing of starting the engine. Therefore, heat needs to be supplied to the internal combustion engine for a long period, when the timing of starting the engine is being delayed for some reason. The amount of heat accumulated in the regenerator is limited, and therefore it is important to utilize the heat effectively to supply heat to the internal combustion engine for a long period.